<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			* {
				margin: 0; /*将所有的元素边距都设置为0 */
			}
			#box {
				width: 750px;
				overflow: auto;
				margin: auto; /*让父元素自动设置边距,左右边距相等,即可达到居中效果,水平方向有效 */
			}
			.item {
				width:210px; height: 136px;
				float: left;
				margin: 20px;
			}
			
		</style>
	</head>
	<body>
		<div id="box">
			<div class="item" style="background: url(imgs/01.jpg);"></div>
			<div class="item" style="background: url(imgs/02.jpg);"></div>
			<div class="item" style="background: url(imgs/03.jpg);"></div>
		</div>
	</body>
</html>
